Fluid heat exchange apparatus



May 8, 1951 J. HARVEY FLUID HEAT EXCHANGE APPARATUS 4 Sheets-Sheet 1 Filed Oct. 23, 1947 ATTORNEY May 8, 1951 J. L. HARVEY FLUID HEAT EXCHANGE APPARATUS 4 Sheets-Sheet 2 Filed Oct. 23, 1947.

INVENTOR James L Harvey ATTORNEY May 8,1951 J. L. HARVEY 2,551,945-

FLUID HEAT EXCHANGE APPARATUS Filed Oct. 25. 1947 4 sh ts-sheet :5

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INVENTOR James [.Harvqg BY ATTORNEY May 8, 1951 J. 1.. HARVEY FLUID HEAT EXCHANGE APPARATUS 4 Sheefs-Sheet 4 Filed Oct. 23. 1947 INVENTOR James I Harvey BY m N m n A Patented May 8, 1951 UNITED STATES PATENT OFFICE FLUID HEAT EXCHANGE APPARATUS James L. Harvey, Fanwood, N. .L, assignor to The Babcock & Wilcox Company, Rockleigh, N. 5., a corporation of New Jersey Application October 23, 1947, Serial No. 781,659

Claims. i

This invention relates to fluid heat exchange apparatus, as exemplified by an installation burning a slag forming fuel at high rates of heat release and utilizing the products of combustion therefrom in the generation of superheated steam.

The invention is specifically concerned with improvements in an installation burning a slag forming fuel under furnace temperature conditions conducive to the release and maintenance of ash and molten particles and to the subsequent conditioning of the high temperature combustion products delivered by the furnace. The invention involves a specific apparatus whereby the condition of such high temperature products is quickly changed from a molten state to a solid or semi-solid state by cooling the furnace gases in which the molten solids are carried in suspension. This cooling is accomplished by the mixture with the furnace gases of a low temperature tempering fluid under optimum conditions.

The invention provides an installation adapted for the burning of pulverized coal at high combustion rates and in a furnace of such space restrictions as those imposed by mobile power units, such as steam locomotives, delivering products of combustion carrying suspended residual ash particles in a physical form conducive to sustained high capacity heat absorption by the convection steam generating surfaces.

In a more specific sense, the invention involves a tempering fluid duct structure in which the marginal part of a duct wall across the path of oncoming furnace gases containing suspended molten ash particles, is arranged in a forward position relative to the remainder of that wall so as to promote the optimum tempering of the furnace gases by the tempering fluid by minimizing the concentration of the suspended slag particles at a position adjacent that part of the duct.

Various structural features comprising the in vention are pointed out with particularity in the subjacent claims forming a part of this specification, and for a better understanding of this invention, its advantages and the specific objects attained by its use, reference should be had to the accompanying drawings in which a preferred embodiment of the invention has been illustrated.

In the drawings:

Fig. 1 is a longitudinal vertical section of the steam generator showing one of the forwardly inclined tempering fluid ducts at the outlet of the primary furnace;

Fig. 2 is a partial vertical section on the line 22 of Fig. 4, showing the tempering fluid duct section of the Fig. 1 installation on a larger scale;

Fig. 3 is a transverse vertical section on the line 3-3 of Fig. 2;

Fig. 4 is a horizontal section of the line 4-4 of Fig. 2; and

Fig. 5 is a partial vertical section on the line 5-5 of Fig. 2.

Fig. 1 of the drawings illustrates a water tube steam generator for a locomotive, the height of the installation, from its steam and water drum Hi to the bottom of the slag pan 52, being consequently limited by the restrictions of standard railway practice. The width of the installation is similarly restricted.

As an indication of the adaptability of the illustrative steam generator for railway use, Fig. 1 shows the furnace or combustion chamber M as disposed above the railway track 15. Consequcntly, the furnace is considerably foreshortened in its vertical dimensions, this limitation imposing difficult conditions relative to the burning of the slag forming fuel at high combustion rates.

The entire installation, including the furnace M, is supported by a suitable locomotive frame, and provides for the substantially horizontal flow of combustion gases from the furnace straight through the installation, beneath the steam and water drum IE) to the flue E8, the walls and other boundary surfaces being formed by steam generating tubes connected into the fluid circulation system including the steam and water drum [0 and lower side headers 28 and Fig. 3 indicates the manner in which such circulatory components are arranged, disclosing the opposite Wall tubes 24 and 26 leading from the headers 20 and 22, respectively, to the steam and water drum HI.

The circulatory system providing wall cooled surface for the furnace M also includes the front wall headers 28 and 29, roof tubes 32, front wall tubes 34, floor tubes 36 and 38, and side wall tubes such as those indicated in Fig. 3. The floor tubes lead from lower header 36 along the floor and along the furnace walls to an upper auxiliary header 3! which is connected to the drum ill by header 33, and appropriate connections.

The furnace is fired by a series of pulverized fuel burners such as 46-442, supplied with a mixture of pulverized fuel and primary air through burner tubes 44 and 4E. The burners extend through a secondary air chamber 56 and direct fuel and air into the combustion chamber through downwardly tapering burner throats such as those indicated at 50-52. These burner throats are formed between successive deflectors 3 such as 55-55, supported by the roof tubes in the manner shown and more particularly indicated in the oo-pending patent application of F. G. Bailey, Serial No. 86,172, filed April 8, 1949.

Flames from the burners impinge against a stratum of molten slag upon the rearwardly inclined floor ill] of the furnace, and furnace gas and molten slag particles in suspension flow from the furnace across and between the upright shadow tubes 53"Il (Fig. 4).

The shadow tubes are appropriately connected into the fluid circulation of the installation, and they are arranged in two groups disposed directly forwardly of the furnace gas tempering passages K and M, disposed between the tempering fluid ducts fll'3. The shadow tubes are stud tubes, covered with high temperature refractory material as indicated at 54 and I6. This construction promotes the removal of molten solids by flow downwardly along th refractory coverings of the tubes and toward the slag pan I2.

It will be noted that shadow tubes "I and 83 are offset inwardly from the adjacent walls l8 and 80. This construction, together with the group arrangement of the shadow tubes, forms the relatively wide gas passages R and S directly in front of the forward walls of the tempering fluid ducts I3 and 12. The two groups of shadow tubes are also widely spaced to form the wide central gas passage T forwardly of the front concave wall 82 of the tempering fluid duct II.

After passing the shadow tubes, the combustion products including the furnace gases and their suspended solids flow through the passages K and M between forwardly inclined groups of steam generating tubes arranged to form the tempering fluid ducts l I--I3. The inlets of these ducts, disposed at their lower ends, are appropriately connected with a source of tempering fluid, such as low pressure steam, which may be advantageously exhaust steam from prime mover.

The middle tempering fluid duct ii is delineated by the intermediate stud tubes 8 86 which are arranged in wall formation such as that shown in Fig. 4. Beyond these intermediate tubes, the marginal stud tubes 88 and 99 are forwardly offset as shown in the drawings. All of these wall tubes are preferably substantially uniformly spaced, with the inter-tube spaces closed by high temperature refractory.

The forward walls of the tempering fluid ducts i2 and i3 are of a construction similar to that just described, with the marginal stud tubes 92 and 94 offset forwardly of the remainder of those walls. Thus, the tube 94 is offset forwardly relative to the intermediate tubes 96 and the wall formed therealong by refractory 98. Similarly, the marginal tube c2 is offset forwardly relative to the tubes I65 and the wall formed by the connecting refractory material.

The above described concave construction of the forward walls of the tempering fluid ducts acts to overcome or minimize the tendency of the high velocity gases to carry the predominant proportion of the suspended molten solids through the passages K and M. This construction also promotes the movement of the molten solids towards the ash pan !2 and the slag discharge opening 562. The forward walls of the tempering fluid ducts, by reason of their forward inclination, tend to give such suspended solids downward components, and the flow of such sus pended solids downwardly is increased by the invertedtrough-like construction of the walls.

The rearward walls of the tempering fluid ducts 1 I-'I3 are formed by the rows of stud tubes led-4e? constructed with the intervening rcfractory to form the inclined slots II6I it through which the tempering fluid is transversely injected into the furnace gases and become mixed therewith.

For the purpose of periodically clearing the inclined slots I Ill-I Id of slag accumulations high pressure steam tubes I2QI23 extend into the ducts. These tubes are provided at vertically spaced positions with steam jet nozzles such as I25 and I28 directed toward the adjacent Rearwardly of the tempering passages F. ...1d M are the tube plattens I34 and I33. Tubes forming these plattens have the major parts of their lengths inclined in the same manner as the tubes forming the tempering fluid ducts and each platten consists of six contiguous tubes job are appropriately connected into the do l circulation. Preferably, their upper ends are connected to the steam and water drum it and the lower parts of some of the tubes forming the ducts II -13. Such a connection is in icated at I38 in Fig. 2. These plattens form radiant shields and gas flow deflectors, and they divide the chamber between the bank of widely spaced screen tubes I49 and the tempering fluid ducts into the two zones, the rearward zone I42, being free of transverse tubes or other obstructions. This arrangement promotes the distribution of the furnace gases and the separation therefrom of fly ash which is collected in the subjacent ash pan I44,

After passing between the widely spaced tubes of the screen I49 the furnace gases pass through the flow equalizing space I46 and then between and around the closely spaced tubes of the superheater screen I50. The gases next pass over the closely spaced tubes of the convection superheater I52 and then over the tubes of the bank of upright steam generating tubes I54. Beyond this point, the gases pass across the bank of air heater tubes I56 to the flue I8.

Fig. 3 of the drawings indicates the construction of the installation at a position rearwardly of the shadow tubes and looking toward the lower parts of the furnace gas tempering passages K and M. As here indicated, the wall tubes have floor extensions such as IE0 and IE2 which 50 are reversely bent on opposite sides of the slag discharge opening I02, for connection with the headers 29 and 22, as indicated at I54 and I65. The floor tube sections I60 and IN and the lower parts of the wall tubes 24 and 2-8, forwardly of the tempering fluid ducts have their furnace sides covered with high temperature refractory as indicated at I'I0IIt. However, for the purpose of promoting the cooling of the gases beyond the point of entry of the tempering gases through passages M and K, the upper parts of the wall tubes are bare as indicated at I16 and I18. The roof tube extensions I and I82 of these tubes are similarly bare.

Exteriorly of the wall tubes 24 and 25 are rows of downcomers I84 and I86 connected at their upper ends to the steam and water drum I9 and connected at their lower ends to the headers 28 and 22 as indicated in Fig. 3.

Fig. 5 indicates the manner in which the tubes forming the walls of the tempering fluid ducts are connected to the lower water headers 20 and 22. This figure also.- indicates the longitudinally extending large diameter tempering fluid conduits I90 and I92 which are transversely connected to the lower ends of the tempering fluid ducts by the chamber I94. The ducts I90 and 192 extend along either side of the installation from a transverse conduit I96 receivin tempering fluid from a conduit I98.

For the purpose of maintaining the zone of the slag discharge opening 102 above the fusion temperature of the slag, the slag pan I2 is appropriately connected with a conduit 289 which extends through the larger conduit 19a) to a position Where it is connected to the bypass duct 202 having the Outlet 254 just forwardly of the air heater E56. Bypass flow of high temperature furnace gases from the primary furnace through the slag discharge opening and then to the air heater may be controlled by an appropriately positioned damper.

Although this application discloses the pulverized fuel fired installation for a steam generator in which a tempering fluid is caused to be mixed with the products of combustion in I the furnace, this application is limited to that subject matter with the added construction of the forward walls of the ducts through which the tempering fluid is caused to flow in the furnace. The general organization minus this particular construction of the forward walls of the ducts is claimed in the co-pending application of Ervin G. Bailey and Ralph M. Hardgrove, Ser. No. 86,171, filed on April 8, 1949.

What is claimed is:

1. In a water tube steam generator, a furnace having its boundary surfaces delineated by steam generating tubes and having means associated therewith for burning pulverized fuel at furnace temperatures above the fusion temperatures of the non-combustible in the fuel, a convection section including a bank of spaced steam generating tubes, and inclined tempering fluid ducts extending transversely of the furnace gas flow between the furnace and the convection section and having their walls formed by groups of steam generating tubes connected into the circulation of the generator the steam generating tubes of the front walls of said ducts immediately marginal relative to said passage being offset toward the furnace from the adjacent tubes.

2. Apparatus for conditioning combustion of pulverized coal flowing horizontally in a gas pass from a high temperature furnace to a convection section including closely spaced fluid heating tubes, said apparatus including a fluid cooled furnace adapted to have a slag stratum flowing over its floor to a slag discharge opening, a tempering fluid system including fluid cooled ducts for introducing and mixing a tempering fluid with the horizontally flowing stream of furnace gases between the ducts, said ducts being inclined and extending upwardly and forwardly of said opening through the furnace gases and having opposite tempering fluid discharge ports opening toward the stream of furance gases, and means supplying tempering fluid to said ducts, the forward walls of said ducts (presented toward oncoming furnace gases) having their marginal portions extending forwardly of the remainder of said walls.

3. In a water tube steam generator, a primary furnace having means associated therewith for burning pulverized fuel at furnace temperatures above the fusion temperatures of the non-combustible in the fuel, the primary furnace having boundary surfaces defined by wall cooling steam generating tubes, groups of forwardly inclined steam generating tubes connected into the cirproducts of 7 culation of the generator and arranged to present a furnace gas cooling barrier across the vertical extent of the furnace with a passage between the groups of tubes for the exit of furnace gases from the furnace, said groups of tubes being also arranged to form inclined tempering fluid ducts of relatively large free flow area extending into the furnace and having tempering fluid ports at the sides of said passage, means for supplying said ducts with a supply of tempering fluid for discharge of that fluid through said ports into mixing relationship with the furnace gases, and a convection section including a bank of steam generating tubes and a superheater disposed rearwardly of said tempering fluid ducts, the forward walls cf said tempering fluid ducts having their edge parts marginal to said passage offset forwardly relative to the remainder of the forward walls.

4. In a steam generator, a pulverized coal burning furnace operating at gas temperatures in excess of the fusion temperature of the incombustible residue from the fuel, burners, water cooled tubes defining the furnace boundary surfaces, a convection section including closely spaced steam generating tubes, spaced groups of steam generating tubes delineating the front and rear walls of inclined tempering fluid duets with their outlets leading to furnace gas passages between said groups, and means supplying a tempering fluid to said ducts, the front wall tubes of said groups marginal to said passage being offset forwardly of remainder of the front walls.

5. In a water tube steam generator, a primary furnace having means associated therewith for burning pulverized fuel at furnace temperatures above the fusion temperatures of the non-cornbustible in the fuel, the primary furnace having boundary surfaces defined by wall cooling steam generating tubes, groups of forwardly inclined steam generating tubes connected into the circulation of the generator and arranged to present a furnace gas cooling barrier across the vertical extent of the furnace with a passage between the groups of tubes for the exit of furnace gases from the furnace, said groups of tubes being also arranged to form inclined tempering fluid ducts of relatively large free flow area extending into the furnace and having tempering fluid ports at the sides of said passage, means for supplying said duets with tempering fluid for discharge of that fluid through said ports into mixing relationship with the furnace gases, and a convection section including a bank of steam generating tubes and a superheater disposed rearwardly of said tempering fluid ducts, the forward walls of said tempering fluid ducts being of trough-like formation with their channels opening toward the primary furnace.

6. In a water tube steam generator, a furnace having its boundary surfaces defined by steam generating tubes and having means associated therewith for burning pulverized fuel at furnace temperatures above the fusion temperature of the non-combustibles in the fuel, a convection section including a bank of steam generating tubes, and tempering fluid ducts having outlets directed transversely of the flow of furnace gases between the furnace and the convection section, said ducts having front walls extending transversely of the flow of furnace gases and having marginal portions offset forwardly of the remainder of said walls.

7. In a vapor generator, a furnace having its boundary surfaces defined by vapor generating tubes and having means associated therewith for burning pulverized fuel at furnace temperatures above the fusion temperature of the non-combustibles in the fuel, a convection section including a bank of vapor generating tubes heated by gases from the furnace, and tempering fluid ducts having outlets directed transversely of the flow of furnace gases between the furnace. and the convection section, said ducts having front walls extending transversely of the flow of furnace gases and having marginal portions offset forwardly of the remainder of said walls, said front walls thereby presenting channels opening toward oncoming furnace gases.

8. Apparatus for conditioning products of combustion of pulverized coal flowing horizontally in a gas pass from a high temperature furnace to a convection section including closely spaced fluid heating tubes, said apparatus including a fluid cooled furnace adapted to have a slag stratum flowing over its floor to a slag discharge opening, a tempering fluid system including transversely spaced fluid cooled ducts for introducing and mixing a tempering fluid with the horizontally flowing stream of furnace gases between the ducts, said ducts being inclined and extending upwardly and forwardly of said opening through the furnace gases and having opposite tempering fiuid discharge ports opening toward the stream of furnace gases, the forward walls of said ducts (presented toward oncoming furnace gases) having their marginal portions extending forwardly of the remainder of said wall, and upright shadow tubes connected into fluid circulation and grouped across the furnace gas flow at positions forwardly of the spaces between said adjacent fluid cooled ducts.

9. In a water tube steam generator, a primary furnace having means associated therewith for burning pulverized fuel at furnace temperatures above the fusion temperatures of the non-combustible in the fuel, the primary furnace having boundary surfaces defined by wall cooling steam generating tubes, groups of forwardly inclined steam generating tubes connected into the cirfluid ducts of relatively large free flow area extending into the furnace and having tempering fluid ports at the sides of said passage, means for supplying said duets with a supply of tempering fluid for discharge of that fluid through said ports into mixing relationship with the furnace gases, 9, convection section including a bank of steam generating tubes and a superheater disposed rearwardly of said tempering fluid ducts, the forward walls of said tempering fluid ducts having their edge parts marginal to said passage offset forwardly relative to the remainder of the forward walls to present concave faces to oncoming furnace gases, and upright shadow tubes connected into the fluid circulation of the steam generator and arranged across furnace gas flow at a position forwardly of said passage to direct fused ash particles against the forward walls of said ducts.

10. In a steam generator, a pulverized coal burning furnace, burners, water cooled tubes defining the furnace boundary surfaces, a convection section including closely spaced steam generating tubes extending across gas flow from said furnace, spaced groups of steam generating tubes delineating the front and rear walls of inclined tempering fluid ducts with side outlets leading to furnace gas passages between said groups, means supplying a tempering fluid to said ducts, the front Wall tubes of said groups marginal to said passage being offset forwardly of remainder of the front walls, and upright shadow tubes connected into the fluid circulation of the steam generator and disposed in groups across furnace gas flow at positions forwardly of said passages.

JAMES L. HARVEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 248,759 Kelly et a1. Oct. 25, 1881 394,655 Kayner Dec. 18, 1888 863,597 Freeman Aug. 20, 1907 1,149,739 Devore Aug. 10, 1915 1,319,654 Lee Oct. 21, 1919 1,964,133 Nyffenegger June 26, 1934 

